Recipe for Making a Walrus

How do you help a 2700 lb Walrus conceive? Very carefully. In fact, only a handful of walruses have conceived in captivity over the last century. In the U.S., it is 10 to be exact. But Holley Muraco, a zoologist at Six Flags Discovery Kingdom in Vallejo, has changed all that.

Now a Published Recipe

Holley’s recipe for helping captive walruses to conceive will be published in a major scientific journal, and I am proud to have had a part in this.
Posted here about a year ago, Holley watched the mating patterns and hormonal levels of walruses over 7 years. She cleverly figured out that the male walruses in U.S. zoos, among the few species that breed seasonally, are not fertile at the same time that the female walruses are fertile. She attributed it to a breakdown in the normal breeding signals that are intricately tied to day-night rhythms in the arctic. California is simply not the same as the North Pole, where these animals have evolved over thousands of years. Right next door to Santa. In essence, when it comes to fertility, captive walruses are like ships passing in the night.

The Critical Observation

Nobody in history had observed walrus mating patterns like Holley has done.  It’s no surprise either because walruses live in the arctic cold and breed underwater in bone chillingly cold seas. Her observations led her to a great idea: to hormonally shift the male walrus so that he achieves his peak fertility window exactly when the female walrus is fertile (which is once a year). Holley asked me for advice about drugs, doses and timing based on my experience with human male infertility. Ended up working splendidly with a walrus conception achieved naturally, without the fancy help of assisted reproduction!

The Outcome

From these early efforts, the pup that was expected this past May made it to full term, but was stillborn. It took several days for the unbelieving mother to give up the pup–an incredibly sad time. But, now it is possible for her to get pregnant again, as several other captive walruses around the country already are, after following the new recipe. This reminds me of how truly privileged I am because I have the opportunity to help couples conceive every day by helping nature do what it does best.

Press Release

Six Flags discovery kingdom Biologists Successful in Helping Walrus Conceive

  • Scientific breakthroughs beneficial in better understanding of walrus reproduction

VALLEJO, Calif. – January 19, 2012 – After several years of research, Six Flags Discovery Kingdom recently reached a scientific breakthrough with the conception of one of its Pacific walruses. In the last 80 years only 11 calves have been born in U.S. facilities. The results of the park’s groundbreaking efforts, lead by marine mammal reproductive specialist Holley Muraco, have now been published in the Journal of Andrology.

In this study, the breakthrough formula for walrus conception is revealed. By watching the mating patterns and hormonal levels of walruses over a seven-year period, it was determined that male walruses, one of the few species that breed seasonally, were not fertile at the same time as the female walruses.

The team was comprised of Muraco, Discovery Kingdom marine mammal trainers and staff veterinarians with fertility expertise provided by Dr. Paul Turek, a men’s health and infertility specialist, founder of The Turek Clinic in San Francisco and co-author of the study.

“We simply moved his fertile window to coincide with her fertile window, and let the usual magic happen,” said Muraco.

With Turek’s help, the Six Flags team hormonally shifted the male walrus’s fertile window to coincide with the females.

“When Holley asked me to help with the hormonal approach to moving the male walrus fertile window from spring to fall, I thought ‘let’s try what works with infertile men’ and sure enough, it worked,” said Dr. Turek.

What came to light was that the mating signals of walruses are crossed because their day-night circadian rhythms are different in captivity than in the wild.

“In essence, when it comes to fertility, captive walruses are like ships passing in the night,” said Muraco. “Reproduction in walruses is seasonal and is tied to light-dark cycles. Those cycles aren’t the same in California as they are in the Arctic.”

One reason this important observation took some time to figure out is because walruses live in the Arctic cold and breed underwater in bone-chillingly cold waters where few scientists have dared to go. Therefore, due to this inaccessibility, little is known of the walrus reproduction in the wild.

Additionally, it appears that the method used is generalizable to walruses in other facilities, as the Six Flags team has since helped walruses in other parks to conceive as well. The findings have proven significant; today, there are only 17 walruses in North American facilities, three of viable breeding age that reside in the Six Flags park.

“It’s a great feeling when we are able to improve the fertility of other species through natural methods,” said Dr. Turek, “as this is what we try to do in our clinics as much as we can.”

About Six Flags Entertainment Corporation
Six Flags Entertainment Corporation is the world’s largest regional theme park company with approximately $1.0 billion in revenue and 19 parks across the United States, Mexico and Canada. For more than 50 years, Six Flags has entertained millions of families with world-class coasters, themed rides, thrilling water parks and unique attractions including up-close animal encounters, Fright Fest and Holiday in the Park.

About Paul Turek, MD
Paul Turek, MD is founder of The Turek Clinic and a former professor and endowed chair at the University of California San Francisco. As a men’s reproductive health expert, he has pioneered innovative techniques for treating male infertility, including Testicular Mapping. In addition to his appointment to the Cooperative Reproductive Network Advisory Board, Dr. Turek sits on the Advisory Board for the Men’s Health Network, Fertile Hope and is President-Elect of the Society of Male Reproduction and Urology. He is Chief Medical Officer at MandalMed, Inc, and is also Past-President of the American Society of Andrology and of the Northern California Urology Society and is an Editorial Board member of several journals including Systems Biology in Reproductive Medicine, the Asian Journal of Andrology and the International Brazilian Journal of Urology.

A complete biography of Dr. Turek is available on Wikipedia at

About The Turek Clinic
The Turek Clinic, founded in 2008, is a men’s reproductive health practice specializing in male infertility, vasectomy, vasectomy reversal, varicocele repair and other minimally invasive procedures using innovative and cutting-edge techniques. For more information, visit, or right here on Dr. Turek’s blog,